Investigation of scandate cathodes: emission, fabrication, and activation processes

Top-layer cathodes have been shown to exhibit work function values in the 1.5-eV range near 1100 K. Emission from cathodes made by sputter deposition of a Sc/sub 2/O/sub 3//W layer on top of an impregnated cathode were limited by the deposition conditions that cause dissociation of Sc/sub 2/O/sub 3/ and/or formation of volatile oxides of W. Pure Sc/sub 2/O/sub 3/ layers were also activated by an external Ba source to the value of the work function reported above. These results and activation mechanisms and characteristics that are peculiar to the Ba-O-Sc surface are discussed.<
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